I think this is the heart of the matter. Why are people disengaging? I have the same experience as you in central Austin which, while not NYC, is still one the biggest cities in the US. I encounter people I know everywhere I go. The grocery store, theater, bar, etc. But I'm engaged in my community. I think there's something else at play here. I suspect many people aren't interested in engagement and are seeking out ways to retreat. Clearly in your rural Texas town someone could still buy a house miles away from anyone and not engage at all. I wonder if people aren't doing so, or if they do so in such small numbers that you don't really notice.